AIM:To determine the ultrastructure of junction areasbetween neurons and astrocytes of supraoptic nuclei in ratsorally administered 30 g/L NaCl solution for 5 days.METHODS:The anti-connexin (CX) 43 and anti-CX32 doubleimmunoelectromicroscopic labeled method,and anti-Fos oranti-glial fibrillary acidic protein (GFAP) immunohistochemistrywere used to detect changes in the junctional area betweenneurons and astrocytes in supraoptic nuclei of 5 rats after30 g/L NaCL solution was given for 5days.RESULTS:A heterotypic connexin32/connexin43 gapjunction (HGJ) between neurons and astrocytes (AS) in ratsupraoptic nuclei was observed,which was characterizedby the thickening and dark staining of cytomembranes witha narrow cleft between them.The number of HGJs and Foslike immunoreactive (-LI) cells was significantly increasedfollowing hyperosmotic stimuli,that is,the rats wereadministered 30 g/L NaCl solution orally or 90 g/L NaCl solutionintravenously.HGJs could be blocked with carbenoxolone(CBX),a gap junction blocker,and the number of Fos-LIneurons was significantly decreased compared with that inrats without CBX injection,while Fos-LI ASs were not affected.CONCLUSION:HGJ may be a rapid adaptive signal structurebetween neurons and ASs in response to stimulation. AIM: To determine the ultrastructure of junction areas between neurons and astrocytes of supraoptic nuclei in ratrally administered 30 g / L NaCl solution for 5 days. METHODS: The anti-connexin (CX) 43 and anti-CX32 doubleimmunoelectromicroscopic labeled method, and anti-Fos oranti-glial fibrillary acidic protein (GFAP) immunohistochemistrywere used to detect changes in the junctional area betweenneurons and astrocytes in supraoptic nuclei of 5 rats after 30 g / L NaCL solution was given for 5days.RESULTS: A heterotypic connexin32 / connexin43 gapjunction (HGJ) between neurons and astrocytes (AS) in ratsupraoptic nuclei was observed, which was characterized by the thickening and dark staining of cytomembranes witha narrow cleft between them. The number of HGJs and Foslike immunoreactive (-LI) cells was significantly increased after hyperosmotic stimuli, that is, the rats were administered 30 g / L NaCl solution orally or 90 g / L NaCl solution inravenously. HGJs could be blocked with carbenoxolone (CBX), a gap junction blocker, and the number of Fos-LIneurons was significantly decreased with that inrats without CBX injection, while Fos-LI ASs were not affected. CONCLUSION: HGJ may be a rapid adaptive signal structure between neurons and ASs in response to stimulation.